A new study using centuries-old coral records has provided fresh evidence that human-caused global warming is making El Niño events more intense.
Researchers examined living and fossilized corals from the Galápagos Islands to reconstruct changes in Pacific Ocean temperatures over roughly the past 1,000 years. Because corals preserve chemical signatures linked to ocean conditions as they grow, scientists can use them as natural records of past climate patterns.
The findings indicate that El Niño variability has increased substantially since the preindustrial period. Researchers found that the phenomenon has become about 36% more variable compared with conditions before large-scale industrialization, while much of the increase has occurred during the past several decades.
El Niño is a naturally occurring climate pattern that develops when unusually warm surface waters spread across the central and eastern tropical Pacific. It can influence weather far beyond the Pacific, affecting rainfall, temperatures, storms and drought conditions across different parts of the world.
The study suggests that the relationship between global warming and El Niño may work in both directions. El Niño can temporarily push global temperatures higher, while a warmer planet may also make major El Niño events more powerful.
Stronger El Niño Could Mean More Extreme Weather
The implications extend well beyond ocean temperatures. Powerful El Niño events can disrupt established weather patterns, increasing the likelihood of drought in some regions while producing unusually heavy rainfall and flooding in others.
The developing 2026 El Niño has already attracted considerable attention because ocean temperatures in the eastern tropical Pacific are exceptionally high. NOAA reported in August that there was a greater than 90% probability of a very strong El Niño during the Northern Hemisphere fall and winter, with forecasts indicating the possibility of an unusually intense event.
Countries around the Pacific are preparing for potential consequences. In Peru, authorities have warned that approximately 1.2 million people could be exposed to risks associated with El Niño, including flooding and mudslides. Officials have identified hundreds of vulnerable locations and have begun preventive measures ahead of the expected intensification later in the year.
The consequences can also reach food supplies, water resources and economies. Extended drought can damage crops and reduce water availability, while excessive rainfall can destroy infrastructure and agricultural land.
Scientists are particularly concerned because El Niño is developing against a background of already elevated global temperatures.
Coral Reefs Face Another Major Threat
The research is especially significant for coral reefs, which are highly sensitive to changes in ocean temperature.
When seawater becomes too warm, corals can expel the microscopic algae living within their tissues. This process, known as coral bleaching, leaves corals weakened and vulnerable to disease and death if stressful conditions continue.
NOAA monitoring has already recorded elevated bleaching alerts in several reef regions during August 2026, including areas of the Caribbean and Pacific.
Scientists say repeated heat stress is becoming increasingly difficult for reefs to withstand. A recent global assessment found that the average time between major coral bleaching events has shortened considerably, leaving less opportunity for damaged reefs to recover.
The combination of climate change and stronger El Niño events could therefore place additional pressure on already vulnerable marine ecosystems.
The new findings do not mean that every future El Niño will automatically become stronger. Natural climate variability remains complex, and scientists continue to study how different factors interact. However, the long-term coral record adds another important piece of evidence that human-driven warming is altering a natural climate system.
As the current El Niño develops, scientists and governments are watching conditions closely. Improving early-warning systems, preparing vulnerable communities and reducing greenhouse gas emissions could help limit the risks associated with increasingly extreme climate events.
